Side draught carb

My carb rubbers are pretty badly perished on my XZ400 Vision. As they seem to be unobtainable I had the idea of fabricating a side draught manifold from aluminium tubing and flat plate and fitting a single CV carb off something like a 400-500cc single. Has anyone tried something like this or is it just one of those stupid ideas I should have kept to myself?

no Idea is a stupid one until you havent asked it and it screwed the pooch!! Im sure people will know more than me, but if its airtight,,should work.. sure its a 400?? I never heard of one.. doesnt mean they dont exist, its just new to me.. On the virago site I belong too,, (yes I own one of those too) THey have a single carb set-up and people rave about them.. I dont know about the vision in particular, though, so wait for one of the gurus to weigh in..

One of the guys had a good post going over at Riders of Vision about modifying his carbs. I think he used some off a Virago. Those posts are currently not available though. You are pretty much limited by your budget and skills as far as adding/modifying the intakes and carbs.

One solution to fixing the boots is to paint them with "liquid electrical tape". It works pretty well on most boots unless they are totally crumbling apart. I did my first set with it and it worked quite well. Keep an eye on ebay as they tend to pop up every now and then and ask in the parts needed section of this forum. Someone may have a useable set they may be willing to part woth or trade for.

Glyn (I believe), in New Zealand, retrofit a Weber on his XZ550 and at last report, he had the jetting just about licked.

The XZ400 was available in Europe, Asia and Australia / New Zealand markets. Many countries in those areas have graduated licenses with cc limits for beginners, intermediates & full licenses. Also, there are often registration cost savings for buying & riding smaller displacement bikes. The XZ400 would not have sold at all in the US, so the marketing decision not to sell it here was valid.

I posted pics 5 or 6 years ago , on the ROV forum, of a Honda 500cc Vtwin with a "custom built " manifold. It consisted of some 1 1/4 inch PVC tubing. The carb mount end pointed forwards , to the front of the bike. Some kind of CV carb was mounted on the end of the plastic tubing. I hooted when I saw it , but it did work ! The bike ran OK and had for several years

I'm not sure if the 400 uses the same boots as the XZ550, but if it does than like AKVision stated, you can still buy boots. One, seems to be available on several Yamaha NOS sites. For the other rare boot, it took a while but I was able to purchase it from http://www.cmsnl.com/. They must have ordered it from somewhere.

In terms of availability from non OEM sources, every few months I see a set of aftermarket boots on ebay.

I've not tried the electric tape approach but I've read several people swear by it.

Hi RickI have fitted a Weber IDF downdraft carb to my bike, and except playing a little with the jetting it has worked perfectly since day 1. If you want full info, pics of my manifold etc please drop me an e mail to pickteam@xnet.co.nz

I battled on with the standard carb, stripping/cleaning a number of times and couldn't get it right. It is an 82 however with the worst carb set up I believe. I think a single carb would work, even an old SU with a good splitter type manifold. However our bikes are designed to have a downdraft carb. It is a high performance bike (for it's day), so you want to keep that airflow as clean as possible to maintain the performance. A single carb would probably give better mpg at the cost of acceleration, I would think.

The Weber IDF is made out of good alloy and all the jets/venturi's etc are easy to get at and change. It is also almost identical to the Mikuni is size so fits under the tank with a K&N mesh filter with room to spare. I made up my own manifold, first in steel and later in alloy. For an Engineer it would not be a big deal. I adapted an old alloy car inlet manifold and made up alloy adaptor plates and stubs myself. Had a good welder weld them all together. My set up still retains the Yamaha inlet rubber connectors also. Alot of the guys on the ROV site seem to have no problems with the carbs, but plenty do. I know it is the single best thing I have done to my bike.

I'd really be interested in seeing the info. I've heard so much about it but have never seen how you did it. Would you mind, or would you mind me, posting it on the website. If you have it in a form thats not easy to post, you can email it to me and I can format it so it will work on the website.

Yes that's my carb Brian thanks for that. The original car manifold can be seen with the B/C stamp on it. I chose it because the centres were not too far off from the Visions.I took thick alloy plate and turned out the centre to match to the manifold centre, this is what the carb is bolted to.It was important to have this welded dead flat so there would be no gaps or the carb body would not distort, once the carb attachment bolts are tightened up. Since the top plates are separate and not joined this requires a good welder (ie not me).The base where the manifold fits into the rubber boots needed a couple more plates and stubs making. All done on my trusty 1950's lathe. I made the stubs an interference fit to the plates to make sure they were well positioned etc. I'll send YellowJacket some more WIP pictures later to give a better idea of what I am trying to explain. I positioned the carb the best I could between the frame rails. I had to compress one rail (the left one) ever so slightly to squeeze it in. I also had to take a little metal off the rear top engine steady. The throttle cable is a one off with a large adjuster in the middle of the cable. The carb has no choke. I had one fitted but it got too cluttered so I took it off. Not really needed. There is still about one inch to spare between the tank and the top of the filter.